Internal-combustion engine



5 SheetsfSheet 1 H( O. EWING INTERNAL COMBUSTION ENGINE Filed Feb. 27 1922 Nov. 10, 3925- Nov. 1o, 1925 1,561,442 H. O. EWING INTERNAL coMBUsTIoN ENGINE:v

Filed Feb. 2v; 1922 '3 sheets-sheet 2 Nw l@t 1925- 1,56l,442 H. o. EWING. l

INTERNAL COMBUSTION ENGINE Filed Feb. 27I 1922 5 Sheets-Shed 5 liL w s. N

l y (j nvenfhn, mz'zj Patented Nov.- 10, 192.5.j

, UNiTEDsrA'rss PATENT orifice.

HERBERT O. EWING, 0F MIDDLEPORT, OHIO.

INTERNAL-COMBUSTION ENGINE.

Application filed February 27, 1922. Serial No. 539,676.

An object of tliisinvention is to provide a vacuum exhaust two-cycle engi-ne having novel components constructedto insure perfeet performance undei'l all coiiditionsoi operation and especially when operating under a .light load. l

Another object of this invention is to provide a vacuum exhaust two-cycle engine having itsI operating components .so coordinated with relation to its intake and exhaust iristruineiitalities-as to insure the maximum elliciency of performance and economy during all phases ot operation.

A further ohject ot this invention is to provide a vacuum exhaust internal combustion engine capahle'oil producing a high i vacuum within a vacuum c linder to receive the exhaust gases from the power cylinders ot the engine, v y ,f

A further object othis -invention' is to provide a two-cyele Vaeuum exhust'f'internal combustion engine otv gcnerallyvimpfed. construction, `whereby the device w'll,-.'l ie.`. simple, duri'ibleand inexpensive in construe' `tion, aswell as practical and serviceable in use.

'lVith the foregoing and other objects in view which :will appear as the description. proceeds, the inventi'i-rir resides 'i'n the Vcomhinationand arrangement of parts and in the details ot' construction hereinafter described and claimed, it being understood that, within the scope ot what iS claimedg'changes in the pr oise embodimentot'the invention shown can be made Without departing' from` the spi-rit of the invention,

The invention has bhen illustrated inits preferred embodiments in the accompanying drawing, wherein:

Figure l is a Vertical sectional .view, parts appearing in elevation.

Figure 2 is a transverse sectionaLview taken, on t`he`line 2f-2of Figure 1.

Figures f and 4 are-diagrammatic views illustrating` different phases of operation of the device. Y

Figures 5, 6 'and 7 are diagrammatic views depicting the relation existing between the crank shaft' and the intake and exhaust instruinentalitics during different stages of a4 cycle of operation.

Referring to the drawings, 10 designates 65 a crank case of an internal'combustion` engine, having a crank. shaft/ 11 journaled thereon. A cylinder block is secured tothe crank case 10 and comprises a primary or power cylinder 12 ot' relatively small bore 70 formed at that end of the cylinder block which isremote from the crank case, anda vacuum chamber or cylinder 13 of larger diameter is formed in the cylinder block adjacent the crank case'and communicates 'lo therewith. These cylinders communicate with each other and are disposed in axial alignment and the head A14- ofthe cylinder 12 is rounded in order to aid' in properly distributing the fuel charge, thretided aperture is formed in the head 14 t at one side of its c'enter tor the reception of the usual spark plugP.

an intake port 15 extends'inwardlyfand While a 480 upwardly through the wall of the cylinder 35 12 from un intake housing or manifold 16,l and a combined transfer and exhaust port 17 leads from the primary cylinder 12 to the vacuum cylinder 13. 'The intermediate portion of the exhaust port 17 coinmuni- 00' Cates with the' interior of any exhaust housing or Lmanifold 18, and the outlet 19 of this manifold is oi'set laterally in o'rder that 4valve supporting members may be carriedhy the housing. The valve supporting meins bers comprise 'adially aligiedbearings 2O and 21 'which slidahly receive the stein 22 of a tappet ordisk `valve 23, and this valve 23 cooperates with a seat 2-1formed at the pointof communication between the exhaust port 17 and the' exhaustmanifold 18. A portion of the stein 22 isthreaded to receive an adjusting nut 25, and a helical spring 26 ispositioned between the adjusting nut 25 and the inner face'of-tlie outer-valve stein hearing 21. By this arrangement the v'alve stem hearing 20-is positioned exteriorly of f the valve 23 so that when this valve is closedthere can be no leakage past the valve stem f' to the interior of the engine.

A composite piston structure is provided and comprises a Aprimary piston J'slidable,l

relation heli-myn the piston El?, intake port l and exhaust port 17, the erank Shaft l1 is oll'set by journaling il lo the rranhV ease, at

points to one .side ol' the axes ol the evlinders 1;' and lil, as indient-ed at l, and this rranhV .shalt ia operably connected to the pistons through the niediuln ol a ronnertinpr rod or pitinan 3Q.

This crank shal't ll is also provided with relatively lone` Crank arms in order lo impart a relatively long; ,stroke to the primary and serondary pistone4 2 and lil.

yl"he cylinders l2 and li are provided with radial cooling; line, and since the eylinder l2 i. ubjeetei'l lo higher temperature, than the ey inder lil, il. is provided with relatively longr tins $53, and the cylinder lil, whieh during' operation is expoaed to les: heal than eylinder lil. is provided with .shorter lins 254. b'inre the raeuuni eylinder lil is neri .sarily larger than the primary cylinder, itr,4 relatively short tins are proportionlwl to terminate at the .saine distanee from the axes of the rylinders as thel terminals oll the long uns i, so that the general eonlour of the terminalel of the tins, 232% and 34 forni a cylinder. '.l`l'erei'ore in multimylinder enginesthe rylinde ,s may be placed very close together and at the saine time providing r the primary eylinder, which is subjected to the most heat, with relatively long tins o aid in radiating` the heat. The outer or head end of the eylinder 12 provided with longitudinally extending' tins fill r sposed at right angles4 to the fins 2li-l, thereny greatly inereasing the radiatingr surface at this pointnwhieh is obviously the hottest portion of the eylinder during;- operation.

ll is highly advantageous that. engines of this type be designed lo operate in restriel ed sl'iaees, such as the limited apaee beneath a washing` machine, domestic mills and the like, and to this end l have so eonstrueted the entire frame of the engine that the eylinders 12 and 13 will be slightly inclined, in which position the uppermost portions of the engine, sueh the vulve structure andthe` fly wheel 35, will be disposed approximately an equal dietaneeI from the ground or .supp'ntimgr base 'for the engine. In this poeition, the space provided by elevating the eylinder end ot' the try i is utilized by placlinor tie fuel supply ianli 13G under the eylinder, and the iuel is fed from the tank 3G through a earhureter 37 and supply pipe to the intake housing 0r manifold 1G, the ear bureler 37 also being' placed beneath the cylinders, Thus. it is obvious that the entire deriee may be plaeed in a very restricted space; and as shown the upper portions olf the highest eoniponents of the device will lie 'i'i an approximately horizontal plane so that the entire deviee may be readily placed under a washingr inaehineor other struel ure. indirated hy the dotted line in Figure l.

ln operation, a 'fresh eharge of' l'uel is drawn in through iluport 15 aud is unil'oruily distributed within the eylinder l). by means o lthe baille head and rounded eylinder head l-l. 'lhe gases are then eonipreshed and a'lter ignition the l'oree of the expanding Irases more the pistons inwardly, and the seeondary piston 2S ereates a high yaeuuni in the cylinder 13%. As the piston 2T nears the eoinplel'ion of its power stroke the exhaust port 'li' is uncovered and the burnt gases are instantly drawn into the yaeuuni rhaniber lil. At this time the port 15 is uncovered and a new fuel charge is taken, and as the pistons move outwardly the primary piston 2T loses the port 15, and that terminal ol' the port l? which opens into the eylinder 12, while the continued outward movenient ol the .secondary piston 28 forces the valve 22% 'from its seat and drives the burnt ,gases from the vacuum chamber to the at.- niosphere.

When the primary piston 27 begins its power .stroke doing work against an external resistanee, this work is donelat the eX-l pense of the energy in the gas resulting from ils combustion, thus reducing both the temperature and pressure of the gases in the priniary cylinder l". The construction of the vsecondary or `vaeuurn piston 28 and vaeuum rylinder are such that (,luringnr the vacuum producing stroke there iS no communication wl'iaisoever with any space ex terior ot'the yaeuuni cylinder llend the port lT uutil'near the end ol' the vacuum prodiu-in;r stroke, when eon'nnunieation is islablished with the 'working or primary eylinder 12 through the port 17, which is made as short and direct as possible, the .seetional ari-a of this port being made as small as possible and yet allow the gases to pass from the primary cylinder into the vacuum eylinder in the time available, the exact dimensions oi this port being determined by experiment lo suit the eonditions of fuel and engine speed. Trhen the primary piston 27 unrovers the, port 17 and establishes conimunieation between the primary and vacuum cylinders, the eases in the primary cylinder l2 being at a inueh higher pressure than that prevailinpr in the raeuuni cylinder, the gases from the primary cylinder flow into the yaeuum eyliinler with a very high velocity,

lfi

lfi

'\cy inder as is practically possible and conpression stroke, makes it possible to get exceedingly smooth operation at low speeds and light loads.

By starting thc secondary or vacuum pis ton 28 on its vacuum producing stroke from a Joint as near the head ot the vacuum structing this secondary piston and vacuum cylinder to so'cooperate as to sever com' munication betweenI the vacuum cylinder and any space exterior of the vacuum cylinder and exhaust L)ort 17, and by restrictingthe size of this port to the minimum dimensions allowable and still secure exhaust in the allowable time, then the dead air'or gas space at the beginning ot the vacuum producing stroke is reduced to a minimum, and consequently, as the secondary piston moves towards 'the crank case, it produces a very high vacuum with a very small displacement becausethere is practically no residual gas inlthe vacuum cylinder at the beginning of the vacuum producing stroke.

ilhis arrangement is especially advantagcous and essential to successi ul operation for the following reasons:

First':-The time available for the exhaust gases to flow from the working cylinder into the vacuum cylinder from the time the exhaust port opens until the inlet port is uncovered is a small fraction of a, second so-that ifuthe cormnunicating passage between the two cylinders is to l'e made as small.` as possible solas to avoid excessive clearance volume, the velocity o't the cxhaust gases' through' this passage must be very highand since the velocity of any fluid .tlowing from a region of high pressure to a region of low 'pressure is proportional to VYthe square of the dilference in pressures, it is evident that for a given terminal pres-` sure in the working cylinder, the lower the pressure produced in the vacuum cylinder, the more quickly the gases will flow from .the working cylinder into it. If the gases do not flow from one cylinder, to the other in the time available the?, engine fails to ture of the residual gases in the vacuum chamber at the end of the vaciuuuproduc ing stroke will dependI upon the pressure at the end ot this stroke, the lower the pressure the lower the temperature (for a given initial temlicrature).

The lower the temperature of the residual gases in the vacuum chamber at thc'time rlicse gases mix with those coming over from the working cylinder, the lower will be the temperature of the resulting niixt'u're and consequently the lower the pressure ol the mixture resulting in more work being returned to the working' cylindcr during its compression stroke.. i

Third :-l,1'nlcss the pressure in the working cylinder is reduced to below that of the atmosphere and this c vlindcr- .treed ol' burned gases quickly itwill bc impossible to bring in a new fuel charge in the short time. that the admission port is open bccause admission depends upon a sub-atmospheric pressure in the working cylinder while the admission port is open. A low pressure in the vacuum cylinder is therefore necessary for the induction ot a new fuel charge.

The three paragraphs justgiven are reasons why a high vacuum is essential to the successful operation of this engine.

lo so construct the vacuum cylinder and piston as 1o secure the greatest possible vacuum with the smallest possible displacement of the vacuum piston is essential :tor the following reasons:

'lo producea vacuum requires that Work be done. In this coi'istruction, this work comes from the working cylinder and the net useful work is the 'dill'erence between the total work'done in the primary or Working cylinder and tile work done in' produc.,- ing the' vacuum; hence it is essential that the work done in producing the vacuum'be kept as small as possible. rl'he work re nifl llo

quired to produce a vacuuni ol ag|ven prcsdisplacement tosecure the vacuum necessary so Vthat to' secure a high vacuum with the minimum amount ot work requires that the vacuum cylindenbe constructed with as little `clearance as is practically possible. Engines constructed with alarge amount of clearance '.would not function because the work required to producethe necessary vacuum would be more than the Working cylinder isv capable of producing.

The term high vacuum as employed in they description of this invention is generally meant` such a vacuum as could be produced by' eii'ecting practically zero clearance between the secondary piston and the vacuum cylinder head at the beginningr of the vac uum producing .stroke and severing communication between the vacuum cylinder and any space exterior of the vacuum cylinder and the restricted whaust port during the vacuum producingtroke. More speciiically it has been found by experiments that pressures within ythe vacuum cylinder varying between eleven and fourteen pounds per square inch below atmospheric pressure are essential to the successful operation of engines of thisl type.

lVhen the engine is operating under 'a light load. and at slow speed. the pressure of the products of combustion will be re duced to atmospheric pressure within the primary cylinder l2 when the primary pis ton has traveled approximately the distance indicated by the arrow A in Figure 3, and continued movement of this piston, as indicated by the arrow B in Figure 4. produces a slight vacuum within the primary cylinder. After the port ,17 has y been opened, as indicated in Figure 4, the low pressure Within both cylinders will tend to draw in air past the valve steunl bearing 20, but this action is prevented by the described valve construction.

After the vacuum piston QSlias traveled far enough on the compression stroke to relieve the vacuum in the vacuum cylinder then a slight pressure is created in this cylinder which opens the valve 23 and forces the burnt gases from the cylinder to i. the atmosphere. Thus it -is seen that part of the energy utilized in 'creating the vaeuum in the vacuum chamber is restored on the return stroke, thereby producing a balancing action between the two pistons, and when operating under a light load the incoming new fuel charge does .not raise the. pressure within the primary cylinder to atmospheric pressure, then the slight vacuum resulting within this cylinder also aids in lcompressing the new charge and further balancing the cycle of operation.` Front the foregoing it is obvious that this arrangement permits a single port to transfer the gases from the primary cylinder to the vacuum cylinder, and 'to exhaust the gases to vthe atmosphere, and at thesame time seali ing the engine against the admission of the previously exhausted gases.

It has been found by experiment that in vacuum exhaust engines it highly ad-l vanta cous to provide relatively slow opening a d quick closing exhaust instrumentalities and 'the most infinitesimal difterence in the speed of opening and closing the exhaust port will add materially to the ef, ficiency the engine and to this end thecrank shaft 30 has been oii'set relative tothe axes of the cylinder. Referring to the dialgrammatie Figures 5, 6 and 7, it will be seenthat as the piston Q7 moves a distance sutiicient to uncover the exhaust port 17 the crank has traveled through an arc as shown in Figure 5, and while closing this exhaust port the crank has traveled through au arc l). Since the arcl) is shorter than the arc C it is obvious that the port closing aetio is.quicker than the opening operation. lfigure (i depicts the. arc of travel of the crank during the closing operation of the intake port and it is seen that the piston 2T completely covers the port when the crank is approaching the vertical portion of its arc of travel. Consequently the piston speed is being increased relative to the rotary speed of the crank. Arc l, in Figure T. illustrates the travel of the crank while the piston l2i' is Amoving from the closing position oi' the intake port l5 to the lo/sing position of the exhaust port 1T, and iilf'is seen that after the closing of the intake port 15, the crank travels a very short distance, before the exhaust port 17 is closed, thereby aiding in. preventing any of the fresheharge being drawn into the vacuum cylinder with the exhausting burnt gases. Arc (t shows the travel of the crank during the opening of the exhaust port 17 before the opening of the intake port 15, and since the are (lr is greater than the arc ll it is manifest that the ripening of the exhaust port 1T before the uncovering of the intake port 15 is .slower than the closing of the exhaust port 1T after the closing of thc intake port 13, 'lfherefore with this arrangement the high vacuum produced in the vacium chamber 11-3 will remove the requisite portion of the burnt gases from't 1e primary cylinder 12 before the incoming charge is admitted, and after the admission of the new charge and the closing of the intake port 15 the exhaust port is quickly closed tf prevent the dissipation of the fuel charge. ln order to obtain the highest possible vacuum within the vacuum cylinder 13, the pistonsf and Q8 are given relatively long strokes duc to the relatively long crank arms of the crank ll, and tothis end the pistons are given a stroke which is preferably equal' to or greater than the diameter 'of the vacuum cylinder. This long stroke 'permits the ignited fuel charge, when operating under a normal or heavy load, tofexpand to substantially atmospheric pressure within the primary cylinder l2, thereby in suring fuel economy, which action is not possible in the existing two cycle engines having short strokes. The relatively long stroke of the secondary piston 28 creates a vl'iigh Vacuum within the vacuum cylinder 13,-

which action is aided by the restricted exhaust port 17 which only4 has sufficient transverse dimensions to permit the transfer of the burnt gases from the primary to the vacuum cylinder during 'the exhausting i of the vacuum cylinderthen the dead air space at the beginning ot' the power stroke is reduced to a minimum and consequently as the vacuum piston moves towards the crank case it produces a high vacuum because there is only a minimum amount ot' air in the vacuum cylinder and in communication with this. cylinder at the beginning of the power stroke. At the end of the power stroke thev high vacuum instantly draws the requisite portion ot' the foul charge into the vacuum cylinder thereby reducing the pressure' within the primary cylinder 12 to below ati'nosplierieI pressure and Consequently draws a 'fresh fuel charge intothe primary cylinder ot' sutlicient volume to insure coi'nplete charging. A't'ter the requisite portion ot' the foul charge has been v'transferred into the vacuum cylinder 13, the relatively long stroke ofthe sec ondary piston 2S within the riilatively long vacuum cylinder 125 exposes this i'onl charge to .the cooling action of the increased cooling surface of the vacuum eylii'ider thereby"materially reducing the pressure of these foul gases, which action lowers the pressure within the vacuum eylint'ler dui-in,"r a vportion of the return or compression roke to aid in*compressing-thc iresh iuel charge. During the relatively long compression stroke the fresh charge is highly compressed and consequently becomes highly sensitive, but owing to the peculiarly cooled cylinder head 14 preignit ion is prevented. This relatively long stroke aids in positively starting the engine because when the high 'v'aeuun'i thus created is communicated to the primary cylinder i2 it quickly produces sub-atmospheric pressure within the power cylinder thereby drawing in sut' lieient fuel at the end of the first inward 'stroke of pistons to insure positive startiingE when tired at the end otthe compression stroke. I

Having thus described my invention what Iclaimis: V

1. ln an internal. combustion engine, the combination ol" :i primary cylinder, u. vacuh um cylinder positioned in axial alinement4 with the prin'iary cylindert an intake port communicating with thc atmosphere and the primary cylinder through the conventional carburetor, an exhaust port leading from tite primary cylinde'rto the vvacuum cylinder, the terminal of the exhaust port which communicates with the primary cylinder having greater dimensions in the direction of the axes of the cylinders than the ter-,

minal of the intake port which communi- Cates withV the primary cylinder, the ends of the said terminals of the intake and exi haust ports which are disposed "avay from the head ot' the .primary cylinder being disposed equal distances t'rom said cylinder head, a primar piston slidable within the primary cylin er, a secondary piston slidable within the vacuum cylinderl and cooperating with the vacuum cylinder to create a high vacuum within this cylinder, a pitman operahly connected to the said pistons, and a crank shaft journaled eceentrically of the axes of the said cylinders, and operahly connected to thc pitman to move the primary piston during a portion of its power strokoat-a slowerspeed than is attained by the said piston during the same portion ot its compression stroke, thereby causing thel primary piston to open the in take and exhaust ports at a slower speed v'cylinder to draw liuriit gases trom the primary cylinder into the vacuum cylinder, and to draw a new fuel charge into the primary cylinder and operating to segregate the new fuel charge from the burnt gases.

2. In aniiiternal combustion engine the' con'ihination oi' a primary cylinder, a vacilum cylinder vpositioned in azi'ial alinement with the primary cylinder, an intake port communicatingI with the conventionalear- 'oui-eter and the primary cylinder, an exhaust port leading from the primary cy1in der to the vacuum cylinder, and the terminal ot' the exhaust 'port which communicates 100 with the primary cylindcrihaving greater dimensions in the direction of the axes of the cylinders than the-terminal of the intake port which communicates with, the primary cylinder, the ends of the said ter,- ininals of the intake and exhaust which are disposed away from the head of the primary cylinder being disposed equal distances from the head of the primary cylinder, a primary piston slidable within'the primary cylinder, 1l( a secondary piston' slidable within the vacuuin cylinderyto create a high Vacuum in this cylinder, a pitman operably connected to the said pistons, anda crank shattjournaled eecen'trically of the axes of the said cylinders .115 and operably connected to the pitman to rausc this piston during its power stroke to uncover a portion of the exhaust port bei'ore uncovering the'intake port at a slower speed .than said port'ibntof the exhaust port 120 is covered during the return stroke, thereby permitting the high vacuum to draw the foul gases into the Vacuum cylinder through this portion of the exhaust port durmg a longer period of time on the power stroke than during the return stroke.

3. In an internal combustion engine the. combination of a primary cylinder, a' vecuum cylinder disposed in axial alirt'fraent communicating with the primary cylinder and the conventional carbureter, an exhaust port leading from the primary cylinder to the vacuum cylinder and the terminal ,of the exhaust wort which communicates with the primary cylinder having greater dimensions in the direction-of the axes of the cylinders than the terminal of the intake port which communicates with the primary cylinder, the ends` of the said terminals of the intake and rexhaust whichl are disposed away from the head of the primary cylin der being disposed equal distances from the head ot the primary cylinder', a priiiiary piston. slidalile within the primary cylinder and constructed to cooperate with the said ports, a secondary piston slidable within the vacuumcylinder to create a high vacuum within this cylinder during the power stroke `of the primary piston, a pitman operably connected to'the said pistons, and a crank shaftJ journalled eccentrically of vthe axes of the said cylinders to uncover a ortion of the exhaust port before uncovering the intake port at a slower speed than said portion ot' the exhaust port is covered during the return stroke to permit the said vacuuin to reduce the pressure within the primary cylinder to below atmospheric pressure before the intake port is opened and Vthereby draw in a new fuel cliargeduring,r

the period the intake port is opened.

`l. ln an internal combustion engine the combination of a primary cylinder, a Vacuum cylinder positioned in axial alinenient' with the primary cylinder, a primaryY piston slidable within the primary Cylin'dei,

an intake port communicating with the pril-nary cylinder, an exhaust port leading" from the primary cylinder to the Yacuum cylinder7 the terminal of the exhaust port which communicates with the lprimary cylinder haring` greater dimensions in the direction oi the axes of the cylinders thaii ihe terminal ot' the intake port which coinmunicates with the primary cylii'nlcr, said port terminals beingv disposed in such relation to cach other and the primary piston as lo cause the primary1 piston during!l the -power stroke to open the exhaust port yslightly in advance ol opening the intake port. a secondary piston slidable within the vacuumcylinder and cooperating with the racuilun cylinder to produce a vacuum within (his cylinder, a pitinan yopcralily connected `to the said pistons, and a crankshaft jouri1. v speed than said po closed toperinifj I. wm

yaeiiuni created within the 4racir-mi erf lto draw burnt gases from the primary inder cylinder into the vacuum cylinder, and to draw a new fuel charge into the primary cylinder and operating to segregate 'the new fuel charge from the burnt gases.

5. In an internal combustion engiifi "the combination of a primary cylinder, a num cylinder positioned in axial alincment with the primary cylinder, a primary piston slit.- alile within the primary cylinder, an intake port communicating with the primary cylinder, an exhaust port lea-dingor from the primary cylinder to the vacuum cylinder, the terminal ofthe exhaust port which communicates with the primary c; inde-i' havinggreater dimensions in the direction of the axes of the cylinders than the terminal et the intake port which communicates with the primary cylinder, said port terminals being disposed in such relation to each other and the primary piston as to cause the primary piston during the power stroketo open the exhaust port slightly in 'advance ot openinter the inta et port, a seconda y piston slidable Within the -racuuin cylinder to produce a Vacuum in this cylinder, a pitman open ahly connected to the said ;,\istons, and a crank shaft journaled eccentrieally of the axes of the said cylinders and operably connected to the pit-man to cause the primary piston during its power stroke to uncover a portion of the exhaust port before nncoxeringr the intake port at a slower speed than said portion of the exhaust port covered during the return stroke, thereby 'permitting the vacuum to draw the foul nasi@ into the vacuum cylinder tl'irough this pirion o'l the rexhaust port during a longer pri-Lid :it time on the power stroke than during; the return stroke.

U. ln an internal coinlnistion engine the comhiii ation of a primary cylinder, a vacuum cylinder pesitioncil in axial aliiiement with l i l e primary cylinder, a primary piston inidalle within the primary cylinder, an .intake port coiinminicaling with 'the primary cylinder, an exhaust port leading.; from iin.: pri- .mary cylinder 'to the vacuum cylinder, 'the terminal of the exhaust port which rommuniiates wi1h the primary cylinder ring greater dimensions in the direction ol the axes ol the cylinders than the ierminal ot the intake port which coninnmiral'rs with lie primary cylinder, said pmt tiriniiials being disposed in such relation 'io each other and the primary piston as to canse the p1 imary piston during they power strolie'i'o open the exhaust port slightly in adrai :e of opening the intake port, a secondary piston r flalile within the vacuum cylinder.' to crea racuuin w`"i i.|.=, tiri: ylinder durinr,t power s"roke :gli tin: priu'iary piston` a nan o1 rahly conne-rt il to the said pifand a crank shalt iourniill-"d Ween-- Btl ill

trically ot' `the axes of the said cylinders and operably connected to the pitinan 'to' canse the primary piston during; its power stroke Ato uncover a portion of the exhaust port before uniform-'inethe intake port ata slower speed than said portion et the exhaust port is covered during' the retarnstroke to perniit the said rae-ouin to reduce th'e pressure within thc primary cylinder lo lielow almospherie pressure before the intake port is opened and thereby draw in a new fuel charge during the period the intake port is opened.

7. In a two cycle internal combustion en- `eine. the combination of a power cylinder havingr a piston connected to the cranl; shat and a vacuun'i cylinder having,r a piston also connected to the crank shaft, said piston havingsubstantially zero clearance with the top of the vacuum cylinder, an intake port for said power cylinder thru `which a 'fresh charge is aspirated, an exhaust port from the power cylinder to the vacuum eylini'ler thru which all o'l the spent gases are drawn into the vacuum cylinder for subsequent exhaust to the atmosphere, said two portsl be- .inbr controlled by the power piston, and being so arranged that they are opened approxiinately at the end of the power stroke, the exhaust port opening before and closing after the opening' and closing' olf the intake port.l

8. ln a two cycle internal combustion engine, the combination olf a power cylinder having a piston connected to the crank shaft 4and a vacuum cylinder haring a piston also connected to lhe crank shalt, said piston having substantially :cero cicarance with the top olf .the vacuum cylinder, in intalie port for sail power cylinder thru` which a fresh charge is aspirated, an exhaust port from the power cylinder to the vacuum cylinder has been drawn in and the admission port i tl. In a two cycle internal combustion engine, the combination of a power cylinder havingr a piston connected to the crank shaft and a. vacuum cylinder having a piston also connected to the crank shaft, said piston haring substantially zero clearance with the lop olf thc vacuum cylinder, an intake port l'or .said power cylinder thru which a fresh charge is aspirated, an exhaust port trom the power cylinder to the vacuum cylinder thru `rhich all of the spent gases are drawn into the vacuum cylinder for subsequent exs haus-l. lo the atmosphere, said two ports beinecozurollcd by the powerl piston, and beingr so arranged that they are opened approxiniately at the end of the power stroke, the exhaust port opening,r before and closing after the opening and closing of the intake port, the parts being so proportioned that when the two cylinders are in communicalion the pressure in the .VacuumY cylinder' never 'exceeds that in the power cylinder.

ln testimony that I elaiin the foregoing as my own, l have hereto affixed my signature.

HERBERT O. EWING. 

